Semiconductor device geometries have dramatically decreased in size since their introduction several decades ago. Modern semiconductor fabrication equipment routinely produce devices with 45 nm, 32 nm and 28 nm feature sizes; new equipment is being developed and implemented to make devices with even smaller geometries. The decreasing feature sizes result in structural features on the device having decreased spatial dimensions. The widths of gaps and trenches on the device narrow to a point where the aspect ratio of gap depth to its width becomes high enough to make it challenging to fill the gap with dielectric material. The depositing dielectric material is prone to clog at the top before the gap completely fills, producing a void or seam in the middle of the gap.
Over the years, many techniques have been developed to avoid having dielectric material clog the top of a gap, or to “heal” the void or seam that has been formed. One class of approaches typically involves separate depositions surrounding etch back processes. This results in a dep-etch-dep sequence which may impose tighter process specifications for both deposition and etch. Another approach has been to start with highly flowable precursor materials that may be applied in a liquid phase to a spinning substrate surface (e.g., SOG deposition techniques). These flowable precursors can flow into and fill very small substrate gaps without forming voids or weak seams. However, once these highly flowable materials are deposited, they may need to be cured and hardened into a solid dielectric material.
There is a need to produce alternative gap-filling films having less stress by modifying the deposition process and/or subsequent processing. There is also a need for these process sequences to produce films having similar properties in narrow and wide trenches. This and other needs are addressed in the present application.